Case presentation

Patient information

A six-year-old female presented with the chief complaint of reduced mouth opening from the age of two years, which had slowly reduced to 2 mm at present. The guardian reported difficulty with feeding, and she was only able to tolerate a liquid diet. There was a history of trauma due to a fall while playing at home at the age of two years. No history of systemic illness or previous surgical intervention was reported.

Clinical findings

Extraoral examination revealed facial asymmetry, fullness of the face on the right side, which was the affected side, flatness of the face on the left side, which was the non-affected side, and chin deviation on the right side. Facial profile was convex due to mandibular hypoplasia. As the interincisal mouth opening was approximately 2 mm (Figure 1), detailed intraoral examination was not possible, but occlusion looked reasonably satisfactory. Temporomandibular joint movements were not palpable on the right side, and slight movements were palpable on the left side.

Figure 1: Preoperative interincisal mouth opening of approximately 2 mm measured using a Vernier caliper (black circle).

Radiographic assessment

Preoperative orthopantomogram (OPG) showed right temporomandibular joint bony ankylosis with obliteration of the joint space and fusion of the mandibular condyle to the temporal bone (Figure 2). Preoperative three-dimensional computed tomography reconstruction demonstrated right temporomandibular joint bony ankylosis with fusion of the mandibular condyle to the temporal bone, resulting in obliteration of the joint space (Figure 3).

Figure 2: Preoperative orthopantomogram showing right temporomandibular joint bony ankylosis with obliteration of the joint space and fusion of the mandibular condyle to the temporal bone (black circle).

Figure 3: Preoperative three-dimensional computed tomography reconstruction demonstrating right temporomandibular joint bony ankylosis with fusion of the mandibular condyle to the temporal bone, resulting in obliteration of the joint space (black circle).

Based on clinical findings and radiographic features, a diagnosis of unilateral right-sided TMJa was established. According to the classification proposed by Sawhney, the condition was categorized as Type III bony TMJa as there was a bony bridge between the mandibular ramus and the zygomatic arch [6].

Surgical management

Under general anaesthesia with fiberoptic nasotracheal intubation, surgery was performed. A standard preauricular approach was used to access the temporomandibular joint. Incision was taken through the skin and subcutaneous tissue; careful blunt dissection was performed through the superficial musculoaponeurotic system with care to preserve the branches of the facial nerve, particularly the temporal branch. The temporalis fascia was identified and incised to expose the zygomatic arch and joint capsule. The periosteum was elevated to expose the ankylotic mass between the glenoid fossa and mandibular condyle.

Osteotomy of the ankylotic mass was performed using a piezoelectric surgical device (Figure 4) rather than conventional rotary instruments. Bone resection was performed under continuous saline irrigation to prevent thermal injury. The use of piezoelectric surgery provided controlled bone cutting and minimized the risk of injury to adjacent soft tissues and vascular structures such as the internal maxillary artery.

Figure 4: Intraoperative image of the ankylosed temporomandibular joint, with osteotomy marking performed using a piezoelectric surgical device at the planned resection site (black arrow).

Approximately 10 mm of gap was created between the glenoid fossa and the mandibular ramus. Ipsilateral coronoidectomy was also performed to eliminate muscular restriction and improve mandibular mobility. Intraoperatively, mouth opening improved to 23 mm (Figure 5). A pedicled buccal fat pad (Figure 6) was used to interpose and obliterate the dead space between the glenoid fossa and the mandibular ramus. It also acted as a biologically compatible cushioning layer between the bony surfaces.

Figure 5: Intraoperative image showing an interincisal mouth opening of 23 mm following gap arthroplasty.

Figure 6: Intraoperative image demonstrating interpositional arthroplasty with placement of a vascularized pedicled buccal fat pad (black arrow).

The patient was followed up regularly for three months after surgery. A structured physiotherapy program was initiated in the immediate postoperative period, and the patient was instructed to perform regular mouth-opening exercises using stacked ice-cream sticks to maintain the surgically achieved interincisal opening. At the three-month follow-up, the patient was compliant with the physiotherapy regimen and maintained an interincisal mouth opening of approximately 20 mm. Functional improvement was evident, with restoration of adequate mandibular movements, and the patient was able to resume a normal diet without difficulty. No clinical evidence of re-ankylosis or postoperative complications was observed during the follow-up period. OPG revealed a gap created in the right temporomandibular joint space (Figure 7).

Figure 7: Postoperative orthopantomogram showing the surgically created gap in the right temporomandibular joint (black circle).